Pouch compositions are known in the art. These compositions have the advantage that they are easy to dose, handle, transport and store. Recently, water-soluble pouches containing cleaning or fabric care compositions have become popular. Usually the pouches are formed by placing two sheets of film together, sealing three edges, filling with the appropriate product, which is typically a gel or liquid, and then sealing the forth edge.
The film material used in water-soluble pouches is necessarily relatively fragile since it must release the product quickly, completely and without leaving residue. To achieve this, the film material must be thin and must have a high water-reactivity. This can lead to problems with the product being released prematurely due to the stresses of production, packing and transportation or due to exposure to a moist environment. In particular, it is difficult to stop the pouches from leaking small amounts of product, a process which is known as ‘weeping’. A weeping pouch exhibits small quantities of the pouch contents on the film surface. Weeping causes the pouches to feel unpleasant to the touch. In addition, weeping pouches can contaminate the surface of other materials through physical contact.
The incorporation of powder into film material is known in the art. See, for example, JP-A-64/29438 (Kao) which describes a polyvinyl alcohol type film obtained by distributing an aqueous dispersion containing 5-30% by weight of a fine powder with a mean particle size of from 0.5-100 microns on one or both sides and then drying the film. The resultant film is said to have good slip properties and adhesion resistance. In addition, powdering of film material is known. See, for example, EP-A-338350 (Asahi) which describes a dusting treatment agent for imparting inter-film lubricity to a film of thermoplastic resin.
The Applicant has found that powdering the outside of the pouch greatly reduces the incidence of weeping. However, if the coating is uneven then it is less likely to reduce weeping. It is also important to minimize the amount of powder used in the pouch making process since it has cost, safety and environmental implications. In addition, consumers do not like water-soluble pouches on which they can feel powder.
The Applicant has surprisingly found that pouches coated with certain electrostatically charged powders show a reduced incidence of weeping. In addition, using such powders provides a more even coating to the film and minimizes the amount of powder used, and hence the above mentioned problems. While not wishing to be bound by theory it is believed that the charge attracts the powder to the film material making for a more even coating and reducing the amount of powder needed.